THIS IS A BRICK HEARTH WITH ANTIQUE BRICK, SO IT IS POROUS.I HAVE TRIED ALL THE COMMERCIAL CRAYON REMOVERS, PLUS GOO GONE WITH NO LUCK. ALL THE CLEANERS JUST SOAK IN. ALSO TRIED IRONING DAMP PAPER TOWEL AND SOME CAME UP ON THE TOWEL, BUT THE BRICK IS STILL STAINED. ANY SUGGESTIONS?